The problem of constructing smooth and durable grade crossings where highways and railroads intersect has been a difficult one to solve on a long term basis. Modern structures normally provide reinforced concrete panels which can either be prefabricated or constructed in place. Because of the normal flexibility of the rails which deflect as a train passes over them, it has not been easy to design such a crossing to provide such flexibility and yet provide the normal rigidity required of a highway surface. Most of the modern structures are directed to the prefabricated panels which are joined in some fashion to the running railroad rails so as to be deflected along with the rails when the train passes over and to remain relatively rigid when automobiles are crossing in the other direction. Typical of the modern devices are those shown in U.S. Pat. No. 3,341,123 to Holthausen; U.S. Pat. No. 3,863,840 to Szarka et al; and U.S. Pat. No. 3,955,761 to Szarka et al. The constructions of the prior art employ special clips or bridging members that can be bolted to the tie supporting the main rail and thereby rigidly attach the prefabricated panel to the rail and its supporting tie so that the entire combination will move and flex together. This is now believed to be an undesirable feature if the proper type of crossties and their associated structures are employed. Another disadvantage of some of these prior art structures is that the panels are positioned as closely as possible to the running rails so as to provide a smooth surface for the automobile crossing, but in so doing open spaces are often left on each side of the rail which may catch foreign objects passing over the crossing and collect dirt and trash that cannot be easily removed.
It is an object of the present invention to provide an improved grade crossing structure that is uncomplicated by clips and bridge members joining the panels to the rails and which leaves no open spaces except that which is necessary for the flanges on the wheels of the railroad cars.